The present invention relates to methods and systems for treating cardiac arrest.
It has been discovered that the medical outcome for a patient suffering from severe brain trauma or from ischemia caused by stroke or heart attack is improved if the patient is cooled below normal body temperature (about 37xc2x0 C.). As understood by the present invention, the medical outcome for many such patients might be significantly improved if the patients were to be mildly or moderately cooled to 32xc2x0 C.-36xc2x0 C. relatively quickly for a short period e.g., 1-2 hours, after an ischemic insult. And if desirable, the patient""s body temperature can be maintain at about 32xc2x0 C.-36xc2x0 C. for approximately 12-72 hours. It is believed that such cooling improves cardiac arrest patient outcomes by improving the mortality rate, in that many organs can benefit from the cooling, and by improving the neurological outcome for those patients that survive.
Systems and methods have been disclosed that propose cooling blood flowing to the brain through the carotid artery. An example of such systems and methods is disclosed in co-pending U.S. pat. app. Ser. No. 09/063,984, filed Apr. 21, 1998, owned by the present assignee and incorporated herein by reference. In the referenced application, various catheters are disclosed which can be advanced into a patient""s carotid artery and through which coolant can be pumped in a closed circuit, to remove heat from the blood in the carotid artery and thereby cool the brain. The referenced devices have the advantage over other methods of cooling (e.g., wrapping patients in cold blankets) of being controllable, relatively easy to use, and of being capable of rapidly cooling and maintaining blood temperature at a desired set point.
As recognized in co-pending U.S. pat. app. Ser. No. 09/133,813, filed Aug. 13, 1998, owned by the present assignee and incorporated herein by reference, the above-mentioned advantages in treating ischemia by cooling can also be realized by cooling the patient""s entire body, i.e., by inducing systemic hypothermia. The advantage of systemic hypothermia is that, as recognized by the present assignee, to induce systemic hypothermia a cooling catheter or other cooling device need not be advanced into the blood supply of the brain, but rather can be easily and quickly placed into the relatively large vena cava of the central venous system. Moreover, since many patients already are intubated with central venous catheters for other clinically approved purposes anyway, providing a central venous catheter that can also cool the blood requires no additional surgical procedures for those patients. A cooling central venous catheter is disclosed in the present assignee""s co-pending U.S. patent applications Ser. Nos. 09/253,109, filed Feb. 19, 1999 and 09/305,613, filed May 5, 1999, both of which are incorporated herein by reference.
The present invention understands that the above-mentioned benefits of hypothermia might be particularly suited for treating cardiac arrest. This is because outcomes for cardiac arrest patients currently are very poor, even when the patients can be resuscitated, since brain damage occurs as a result of the global ischemia caused by lack of blood flow before resuscitation. The severity of such brain damage, as understood herein, can potentially be alleviated by hypothermia.
A kit for lowering a patient""s temperature includes a first catheter that has at least one fluid circulation passageway connectable to a source of coolant. In accordance with the present invention, the first catheter is configured for placement in a patient""s vena cava via a groin entry point. Also, a second catheter has at least one fluid circulation passageway connectable to a source of coolant. As set forth below, the second catheter is configured for placement in a patient""s circulatory system via a neck entry point.
In one aspect, a bolus of cold saline solution is introduced into the brain of the patient through a third catheter to lower the brain temperature quickly. In one embodiment, the third catheter is advanced into the patient""s aortic arch. In another embodiment, the third catheter is advanced into the patient""s carotid artery. In a preferred embodiment, the temperature of the cold saline solution can range from 0 to 37 degrees celsius; although other temperature ranges will be understood by those skilled in the art. The cold saline solution is released into the brain area through the drug delivery port of the third catheter. This third catheter (included in the kit) may also include at least one fluid circulation passageway connectable to a similar source of coolant as the first and second catheters. Alternatives to saline solution will be understood by those skilled in the art. Similarly, the third catheter may be advanced into other arteries that supply the brain with blood, such as, but not limited to, the brachiocephalic artery, the basilar artery, etc.; or the third catheter may be advanced into the various cerebral arteries that are connected to the carotid artery such as, but not limited to, the middle cerebral artery (MCA), the internal cerebral artery (ICA), the anterior cerebral artery (ACA), etc.
In a preferred embodiment, the kit can include the source of coolant. Preferably, the source of coolant includes at least one thermal electric cooler (TEC) for heating or cooling coolant such that coolant is returned to the catheter to heat or cool the catheter. The kit can be incorporated in system that includes a ventilation system, and/or a defibrillator system, and/or a component containing a drug selected from the group consisting of: epinephrine, buffers, antiarrhythmics, and atropine.
In another aspect, a method for treating cardiac arrest in a patient includes defibrillating the patient, and lowering the patient""s temperature using at least one catheter placed in the venous system of the patient.
In still another aspect, a method for treating cardiac arrest using hypothermia includes resuscitating the patient and inducing hypothermia in the patient.
In yet another aspect, a system for treating cardiac arrest in a patient includes at least one cooling catheter that is advanceable into the central venous system of the patient. The system further includes one or more of: a defibrillator, a ventilator, and a cardiac arrest drug delivery device engageable with the patient.
In yet another aspect, a system for treating cardiac arrest in a patient includes at least one catheter that may be introduced into the aortic arch or into the carotid artery of the patient and that can deliver a bolus of cold saline solution into the patient""s brain to lower the brain temperature quickly. The system further includes at least one other catheter that may be advanced into the central venous system of the patient. This central venous catheter is situated in a heat exchange relationship with the patient""s blood supply using coolant which is circulated between the central venous catheter and an external coolant source in a closed loop. The system may also include one or more of: a defibrillator, a ventilator and a cardiac arrest drug delivery device engageable with the patient.
In yet another aspect, the catheter (that may be introduced into the aortic arch or into the carotid artery of the patient for delivery of a bolus of cold saline solution) is also a heat exchange catheter which can circulate coolant between the blood supply of the patient""s brain and an external coolant source in a closed loop either to continue to lower the brain temperature or to maintain the brain temperature at a given threshold as determined by the patient""s caretaker.